Wireless Networking Concepts

By: Forrest Finkler

Computer Science 484 Networking Concepts

Summary

• What is a Wireless Network

• Methods of Securing Wireless Networks• WEP (Wired Equivalent Privacy)• WPA (Wi-Fi Protected Access)• MAC (Media Access Control) Address Filtering

• Security Flaws of Wireless Data Networks

• How to Bypass Security

What is a wireless network

• Wireless Networks Connect Computers Together and Allow Data to Travel Wirelessly Between an Access Point and a Client

What is a wireless network

• Wireless Networks Use Access Points and Clients to Communicate With Each Other

• Radio Communications

• 2.4 GHz (b, g, n) or 5 GHz(a, n) band

• 11Mbps (b), 54Mbps (g, a)128 Mbps (n)

• Allows for movement (roaming) between access points

Securing Wireless Networks

• WEP (Introduced in 1999)• 64 or 128 bit• 64 Bit

• Uses a 40 bit key• 10 Hexadecimal Numbers “F2C7BB35B9”• 10 Hex * 4 bits per number = 40 bits• 40 bits + 24 IV = 64 bits

• 128 Bit• Uses a 104 bit key• 24 Hexadecimal Numbers “2B204A3F1042643E480FDD655E”• 24 Hex * 4 bits per number = 108 bits• 104 bits + 24 IV = 128 bits

Securing Wireless Networks

• Wi-Fi Protected Access• WPA or WPA2• WPA

• 128-bit key and a 48-bit IV• Uses Temporal Key Integrity Protocol (TKIP)

• Better Security Through Dynamic Keys• Based on 802.11i Draft Standards

• WPA2• 128-bit key and a 48-bit IV• Uses Advanced Encryption Standard (AES)

• Uses a Matrix of Bits and Rounds (mathematical operations) to Authenticate Clients

• Based on 802.11i

Securing Wireless Networks

• Media Access Control Address Filtering• MAC Addresses• MAC Addresses are 48 bits and are Unique to Each NIC• Typical MAC Address “00:0F:66:2A:A5:D5”

• Weaknesses• MAC Addresses are Easily Spoofed Using Software• A Very Weak Security Measure Only Should be Used in

Conjunction With WEP or WPA

How to bypass WLAN security

• MAC Address Spoofing (<20 seconds)• ifdown eth0

• ifconfig eth0 hw ether 00:80:FF:FF:98:F5

• ifup eth0

• WEP Cracking (2 min-30 min)• Kismet (captures raw packets(need 20,000 to 500,000 IV’s))

• Aircrack (decrypts packets and finds WEP key)

• WPA Cracking (15 min-∞)• Only Crackable if Using a PSK

• Brute Force Attack

QUESTIONS?